This project addresses statistical problems generated from collaboration with scientists in other program areas and general statistical problems of current interest encountered in biomedical research. This work is a continuing activity of the Branch. In FY99, Branch statisticians have contributed to the following areas of statistical research: statistical screening for diseases in populations; measurement of structural uncertainties in morbidity due to the choice of disease definition; investigation of selection bias in epidemiological surveys; application of time series to longitudinal imaging of the developing brain in heathly individuals and patients with neurological diseases; establishment of reference range values for diagnostics tests; development and application of nonparametric regressions for the analysis of neuroimaging data; the application of recursive partitioning for the evaluation of risk factors in epidemiological studies; and the development of mixture models for clinical time series. Other active areas of statistical research are: the development of nonlinear response models for nondecreasing and time-dependent response functions from multiple compartments; statistical modeling of longitudinal data to identify bench mark events and their time of occurrence in the clinical course of disease; adapting analysis methods for the estimating the level of disease risk for individual factors in the presence of many correlated potential risk factors; the formulation of analysis methods for survival data with time dependent covariates, and new likelihood ratio tests for logistic mixture models in time series. - Statistical methods, neuroimaging, epidemiology, time series, survival analysis, surveys - Human Subjects & Human Subjects: Interview, Questionaires, or Surveys Only